Low friction hydraulic circuit control components

ABSTRACT

A hydraulic control circuit component such as a valve is configured which sliding surfaces. At least one of the sliding surfaces is configured as a single crystal material, such as ruby or sapphire.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/705,013, filed on Sep. 14, 2017, and claims benefit of U.S.provisional patent application Ser. No. 62/394,798, filed Sep. 15, 2016,which are herein incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to the field of fluid control components.More particularly, the present disclosure relates to the field ofhydraulic valves and regulators used to control fluid operated devices,such as other valves and components including oilfield well drilling andproduction equipment, such as surface and subsea blowout preventers.

Description of the Related Art

Hydraulic valves are used to control the opening and closing ofhydraulically operated oilfield well drilling and production equipmentsuch as additional valves or blowout preventers. Regulators are used tocontrol the pressure in a hydraulic circuit to ameliorate pressurespikes which can occur when hydraulic valves in the circuit are openedor closed. Variable orifices are used to selectively pass pressure andfluid therethrough at levels between full fluid flow and pressure and nofluid flow and pressure, and thus regulate the fluid pressure downstreamtherefrom. Pressure regulators are used to maintain a desired pressurein the hydraulic control circuit. The hydraulic control circuitcomponents are commonly provided with redundancy, to ensure that whenrequired to, for example, operate a blowout preventer to close off awell bore being drilled, the hydraulic control circuit will deliver therequired fluid in the required time with sufficient volume and pressureto close the blowout preventer.

One recurring limitation in hydraulic valves and regulators, which usepressurized fluid or an electromechanical actuator to cause at least onevalve component to move with respect to another valve component, isstiction, which is the static friction present between two stationarysurfaces in contact with one another. Typically, the force needed toovercome stiction to allow one surface to move with respect to the otheris greater than the force needed to cause two surfaces in contact witheach other to continue moving with respect to each other once movementtherebetween has started. As a result, it is known in the art that up to20% of the total force, and thus of the total energy, supplied to ahydraulic valve can be taken up to overcome stiction. In the regulator,where dead bands on the order of 20 to 30% are known to occur in currentdesigns, hunting, or oscillating around the outlet pressure setpoint, isa continuing issue affecting the operation of the hydraulic circuit.Pressure oscillations in the line or conduit opened by the valve when avalve is opened on the order of 1400 psi decreases and 600 psi increasesare known to occur.

An additional issue present in hydraulic circuit control components isreliability of the hydraulic control component due to wear and corrosionof the components, caused by the exposure of the components to erosiveand corrosive hydraulic operating fluids, and by relative movement ofthe components with respect to each other. Corrosion and erosion of therelatively moving parts can generate debris tending to cause thesecomponents to become locked, or move erratically, with respect to eachother, and corrosion, erosion and wear can cause sliding interfacebetween components to leak, reducing the effectiveness and reliabilityof the hydraulic control circuit component. In either case, thehydraulic circuit component will require repair or replacement, which ina subsea environment is expensive where servicing of the componentsoften requires the use of a submersible robot to remove or service ahydraulic circuit component. To prevent the hydraulic control circuitfrom becoming non-functional as a result of a failure of a hydrauliccontrol component, and to reduce the number of service operation periodsin which a submersible robot is used to replace components, subseacontrol systems often have even greater redundancy requiring even moreredundant hydraulic circuits and attendant components, leading to evengreater cost.

To help reduce wear, the hydraulic control circuit components whichinclude sliding contact surfaces have been made from, or coated with,carbide materials. However relatively high stiction occurs between twoclosely fitted, but movable with respect to each other, carbidesurfaces. As a result, to operate these hydraulic circuits, fluidmaintained at relatively high pressures is required. A substantialamount of energy is used to pressurize the fluid, and large accumulatorsare needed to store the fluid under the high pressure. Because of theneed for redundant components systems, these costs are magnified wherestiction is a large factor in the operational energy needed to operatethe valve.

Additionally, carbide based components are brittle in comparison tostainless steel components, and for example, where two such parts of acomponent must be moved into sealing engagement, slower componentvelocities resulting in lower engagement forces are used to ensure thecomponents does not fracture, crack or create particles of the componentwhich can become lodged between moving surfaces and lock the movingparts in place. As a result, slower valve operation than optimalresults.

SUMMARY OF THE INVENTION

Embodiments herein provide a lower friction and higher wear andcorrosion resistance sliding interface in hydraulic component slidinginterfaces. In one aspect, the sliding interface includes single crystalcoatings or inserts on the part surfaces in sliding contact.

In another aspect, the hydraulic component parts having sliding surfaceinterfaces are configured of a single crystal material. In yet anotheraspect, those parts having a sliding surface are configured of singlecrystal sapphire. Alternatively, one of the parts having a slidingsurface interface is configured of the single crystal material, forexample single crystal sapphire, and the sliding surface of the othercomponent is coated with, or includes an insert forming the slidingsurface, of a single crystal material such as ruby.

In another aspect, the single crystal material can be sapphire or ruby,and one sliding surface can comprise ruby, and the other sapphire,either as a coating, an insert, or the composition of the entire part.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a sectional view of a shear seal style valve;

FIG. 2 is an enlarged view of a portion of FIG. 1, showing the sealcarrier and sealing elements in greater detail;

FIG. 3 is a sectional view of a bidirectional seal assembly and opposedseal plate assemblies wherein the bidirectional seal assembly blocks theoutlet passages of the valve;

FIG. 4 is a sectional view of a bidirectional seal assembly and opposedseal plate assemblies wherein the bidirectional seal assembly is movedfrom the position thereof to allow fluid to flow from an inlet passageto a first of two outlet passages;

FIG. 5 is a sectional view of a bidirectional seal assembly and opposedseal plate assemblies wherein the bidirectional seal assembly is movedfrom the position thereof to allow fluid to flow from an inlet passageto a second of two outlet passages;

FIG. 6 is an enlarged sectional view a bidirectional seal assemblyuseful in the valve of FIG. 1;

FIG. 7 is a sectional view of a seal used in the bidirectional sealassembly of FIG. 6;

FIG. 8 is a graph showing the force required to begin moving the sealcarrier with respect to the seal plate surfaces of the valve of FIG. 1;and

FIG. 9 is a sectional view of an additional valve employing low frictionmaterials in the sliding surfaces thereof.

DETAILED DESCRIPTION

Herein, hydraulic operating valves, regulators and other hydrauliccontrol circuit components are configured wherein internal componentsthereof which move relative to one another or engage one another areconfigured of a single crystal material, such as ruby or sapphire, andas a result lower friction sliding interfaces, less component wear, anda reduction in the wear and corrosion of these components is achieved.Descriptions of applications of the single crystal material in a numberof selected hydraulic circuit control components are provided herein.While not exhaustive of the applicability of the single crystalmaterial, they are intended to provide exemplars of use of the singlecrystal material and not to limit the scope of the invention describedherein.

Referring to FIGS. 1 and 2, a four way, two position valve 10 is shownin section, wherein certain internal components thereof are configuredfrom, or include inserts configured from, a single crystal material suchas ruby or sapphire. In FIG. 3, the valve components that form thesealing and fluid path switching are shown in section, without theaccompanying valve body and attendant operational elements of the valve.The valve of FIGS. 1 and 2 comprises a valve body 100, an inlet body 90,and outlet body 80, a drive actuator 130, a compensation or returnactuator 140, and a seal carrier 150. A shear seal assembly 138 isprovided in the seal carrier 150. The valve body 100 is configured ofstainless steel or other high strength metal, and includes therein theinlet body 90 having an inlet 102 ported, through an inlet body passage104, to a first seal plate 105 having a sealing surface 106 into whichthe inlet body passage 104 opens, and an outlet body 80 having a firstoutlet passage 108 connected, through first outlet body passage 110 to asecond seal plate 111 having a second sealing surface 112 into which thefirst outlet body passage 110 opens, and a second outlet 114 connectedthrough a second outlet body passage 116 to the second seal plate 111second sealing surface 112, into which second outlet passage 116 opens.Inlet body passage 104 intersects first seal plate sealing surface 106generally perpendicular to the planar surface thereof, and each of thefirst and second outlet body passages 110, 116 intersect the second sealplate sealing surface 112 generally perpendicular thereto. The first andsecond outlet body passages 110, 116 are spaced from each other at thesecond seal plate surface 112 by a distance d (FIG. 2).

Body 110 further includes a cross bore 120 extending therethroughgenerally perpendicular to the portions of the inlet body passage 104and the outlet body passages 110, 116 opening into the seal platesurfaces 106, 112. The drive actuator 130 extends inwardly of a firstopening 132 of the cross bore 120 and thus into the body 100, andincludes a drive rod 134 terminating inwardly of the body 110 in athreaded boss 136. An actuator, such as a mechanical orelectromechanical drive, to push the drive rod 134 inwardly of theopening 132, is shown schematically as the force arrow “A”.Additionally, the actuator may be a hydraulically operated piston. Thecompensation actuator 140 extends inwardly of the second opening 142 ofthe cross bore 120 into the body 100. Compensation actuator 140 includesa compensation drive rod 144 which terminates inwardly of the valve 100in a threaded compensation rod boss 146. In the embodiment, a spring,not shown but schematically represented by force arrow S, provides areturn force to re-center the carrier 150 in the valve 10 between theseal plate surfaces 106, 110.

Referring to FIG. 2, the seal carrier 150 is shown in section andenlarged, and includes a body 152 having opposed, parallely disposed,upper and lower surfaces 154, 156, a threaded drive rod opening 158 intowhich the threaded boss 136 of the drive rod is threadingly secured, andan opposed threaded compensation rod boss opening 160, into which thetreaded compensation rod boss 146 is threadingly received. A seal bore162 extends through the carrier 150 and opens through the upper andlower surfaces 154, 156.

As shown best in FIG. 3, bidirectional seal assembly 170 is receivedwithin a generally right cylindrical in section seal bore 162 andincludes a first sealing element 172 located adjacent to the uppersurface 154, a second sealing element 174 located adjacent to the lowersurface 156, and a biasing element 158 interposed between the first andsecond sealing elements in the seal bore 162, and configured to bias thesealing elements 172, 174 outwardly of the upper and lower surfaces 154,156 respectively. Each of the first and second sealing elements 172, 174have a generally right cylindrical outer surface 176 and a bore 178therethrough opening, at the first or second side thereof, respectively,in an outwardly tapered countersink opening 180. The first and secondseal elements 172, 174 are preferably identical within machiningtolerances, and thus interchangeable. The bore 178 opens, at the endthereof opposite to countersunk opening 180, into an enlarged diametercounter bore 182, such that the counterbores 182 of each sealing element172, 174 face each other within the seal bore 162. An alignment tube 184extends inwardly of the opposed counterbores 182 to maintain alignmentbetween the two sealing elements 172, 174 and form a continuous flowpassage between the bores 178 thereof and thus through the seal bore162. A small clearance gap, on the order of 1 to 5 thousandths of aninch, is present between the tube 184 and the surfaces of thecounterbores 182.

The first and second seal elements 172, 174 are, in the embodiment,right cylindrical elements having the same outer diameter, the same bore178 diameter and the same counterbore diameter. However, the innerdiameter of countersunk opening of the first sealing element 172 facingthe first seal plate 105 has a smaller diameter than the countersunkopening 180 of the second seal element 174 facing the second seal plate111. The first seal element thus includes an annular seal face 181having a first area extending between the counterbore 180 of the firstseal element 172 and the outer diameter thereof, and the second sealelement 174 includes an annular seal face 183 having a first areaextending between the counterbore 180 of the second seal element 174 andthe outer diameter thereof. The area of the second seal face 183 isgreater than that of first seal face 181. The opening diameter of thecountersunk opening 180 in the second seal element at the annular sealface is slightly less than the closest spacing “d” between the outletpassages 110, 116 at the second sealing surface 112, and the outerdiameter of the outer surfaces 176 of the first and second seal elements172, 174 is slightly larger than the largest distance “D” across theadjacent outlet passages 110, 116. A biasing element 158, such as thekey seal structure illustrated in FIG. 7 and in co-pending applicationU.S. Ser. No. 14/067,398 filed Oct. 30, 2013, which is hereinincorporated by reference, is located between the back side 186 surfacesof the sealing elements 172,174 to bias them outwardly of the seal bore162. Backing rings 188 (FIG. 6), or other elements to ensure theintegrity of the biasing element, may be provided between the biasingelement 158 and the back side 186 surfaces.

In the embodiment, the first and second sealing plates 105, 111providing the upper and lower sealing surfaces 106, 112 are provided asan insert 190, each having continuation passages extending therethroughto communicate with the inlet 104 and outlet passages 110, 116 of thebody 100. In the embodiment, both of the inserts 190, and both of thetwo sealing elements 172, 174, are configured as a single crystalmaterial. The single crystal material is preferably chosen from among asingle crystal ruby and a single crystal sapphire. In operation, thecarrier 150 is moveable in the direction of arrows A and S, toselectively align the passage formed through the tube 184 and thecountersunk openings 180 therein with the inlet passage 104 and eitherone or the other of the outlet passages 106, 116 to allow flow from theinlet 102 to one of the outlets 108, 114, or to prevent flow from theinlet passage 104 to either one or the other of the outlet passages 106,116 by aligning the annular sealing surface 190 to block the outletpassages 110, 116. These relative positions of the, bidirectional sealassembly 170 are shown in FIGS. 3 to 5. The first and second sealingplates 105, 111 are eutectic bonded to the underlying stainless steelinlet body 90 and outlet body 80 in recesses 107, 111 provided in theoutlet and inlet bodies 80, 90.

In operation, the bidirectional seal assembly 170 is positionable toselectively allow, or block, fluid flow from inlet passage 104 to one ofthe outlet passages 110, 116. In FIGS. 1, 2 and 3, the bidirectionalseal assembly 170 is positioned such that countersunk opening in thefirst sealing element 172 is aligned with the inlet passage, and thesecond seal face 183 overlies, and covers both outlet passages 110, 116.In FIG. 4, the carrier 150 (FIGS. 1 and 2) has moved the bidirectionalseal assembly 170 from the position of FIG. 3, such that inlet passage104 communicated with outlet passage 116, and outlet passage 110 isexposed to the interior volume 200 of the valve, which may be configuredwith a vent passage to thereby vent the pressure in the outlet passage110. In FIG. 5, the carrier 150 (FIGS. 1 and 2) has moved thebidirectional seal assembly 170 from the position of FIG. 3, such thatinlet passage 104 communicated with outlet passage 110, and outletpassage 116 is exposed to the interior volume 200 of the valve, whichmay be configured with a vent passage to thereby vent the pressure inthe outlet passage 116.

FIG. 8 is a graph showing the force needed to move the carrier withrespect to the seal plate surfaces 106, 112 as a function of thepressure at the inlet 102 for different sealing element 172, 174materials and different sealing plate 105, 111 materials. Using thevalve of FIGS. 1 and 2, a load cell was interposed between anelectromechanical actuator and the actuation rod 134, and no springreturn was present, and the force needed to move the carrier 150 fromthe position of FIGS. 1 and 2 to the right or to the left of FIGS. 1 and2 was measured at a series of discrete inlet pressures using a valvewith three different sealing element 172, 174 and sealing plate 105, 111material combinations: Carbide to carbide, carbide to ruby, and ruby tosapphire. In the valve, the first annular seal face 181 had a surfacearea of approximately 0.0091 square inches, and the annular seal face183 had a surface area of approximately 0.0117 square inches. As shownin FIG. 3, the force in pounds—force (lbf) increases as the fluidpressure, in psi on the inlet 104 increases. However, by using a singlecrystal material as the material of the sealing elements 172, 174 and/orthe sealing plates 105, 111 and thus the sealing surfaces 106, 112, asignificant reduction in the initial force, and thus the storedhydraulic energy required to initiate movement of the sealing elements172, 174 with respect to the sealing surfaces 106, 112, is achieved. Forexample, at an inlet pressure of 1000 psi, over 6 lbf are required tomove the sealing elements 172, 174 and sealing surfaces 106, 112 withrespect to each other when both are configured from tungsten carbide. Bychanging one of the sealing elements 172, 174 or sealing surfaces 106,112 to ruby, that force requirement is reduced to approximately 5 lbf,and when configuring one of the sealing elements 172, 174 and sealingsurfaces 106, 112 of ruby, and the other of the sealing elements 172,174 and sealing surfaces 106, 112 of sapphire, the force required tomove the sealing elements 172, 174 and sealing surfaces 106, 112 withrespect to one another is less than 3 lbf, which is less than one-halfthat of the carbide-carbide interface. The relative force required tomove a ruby to sapphire interface will be the same as a sapphire tosapphire interface.

At higher inlet 104 pressures the reduction in force required to movethe sealing elements 172, 174 and sealing surfaces 106, 112 with respectto each other is even more pronounced. At about 4500 psi inlet 104pressure, the tungsten carbide to tungsten carbide interface requiresover 15 lbf to begin moving, whereas the ruby to carbide interfacerequires under 12 psi to begin moving, and the ruby to sapphireinterface requires less than 8 lbf to begin moving. Thus, at the lowerpressure of about 1000 psi, a reduction in force of about 4 lbf, whichis ⅓ that required for the carbide to carbide interface is used, ispossible using a ruby to sapphire interface. At the higher pressure ofabout 4500 psi, a reduction in force of about 8 lbf, which is ½ thatrequired for the carbide to carbide interface is used, is possible usinga ruby to sapphire interface. It is believed that this is due to thelower electrical affinity of the surface of a single crystal material toan adjacent single crystal surface, as compared to that of a non-singlecrystal surface to a non-single crystal, or a single crystal, surface.

Referring now to FIG. 9, an additional use example of the use of asingle crystal material is shown. In this example, the hydraulic controlcircuit component is a variable orifice 200, as shown in U.S. patentapplication Ser. No. 15/191,096, incorporated herein by reference. Inthis device, when fluid pressure at the inlet 218 experiences an upwardspike, that pressure causes a piston 200 to move inwardly of the devicebody 202 causing an external threaded rotor 204 housed in an internallythreaded sleeve 206 to rotate, thereby causing flow passages 208, 210 inthe rotor 204 to partly to wholly in come into alignment withcorresponding passages 212, 214 in a guide sleeve 216, allowingrestricted or full flow therethrough to the outlet 220 enabling thepressure spike to be relieved. Once the excess pressure is reduced a theinlet 218, a spring 222 causes the rotor to return to the conditionwhere the passages 208, 210 therein are no longer fully or partiallyaligned with passages 212, 214, closing of the flow path. In thisdevice, using single crystal materials such as ruby and sapphire as thesleeve 206 and the rotor 204, or as inserts to provide the threadedengagement therebetween, will reduce the stiction resulting in a loweroperating fluid pressure (force) and thus a lower energy to cause thedevice to operate.

Other devices using hydraulically operated pistons, such as a pressureregulator as shown in U.S. patent application Ser. No. 14/837,192, filedAug. 27, 2015 and incorporated herein by reference can also benefit fromthe use of sapphire and ruby components.

As used herein, the use of ruby and/or sapphire as the components of thesliding interfaces results in a smaller dead zone, lower life as aresult of lower wear and high corrosion resistance, and the ability toreduce the size of the stored energy components, such as springs, usedto restore the hydraulic circuit component to its rest state.

As contemplated herein, ruby or sapphire, wherein ruby is a doped formof sapphire, are available in sheet or rod form from various suppliersuch as Saint Gobain of Milford N.H. The sapphire and ruby used hereinwere ½ light band ruby and 4 RA and 2 light band sapphire. The parts,such as the sealing inserts and seal plate surfaces inserts weremachined from these materials using diamond cutters, and then lapped toimprove surface finish. Where the sliding interface surface is an insertattached to another component, such as a sealing plate assembly, onesurface of the insert is metallized, and the metallized surface is thenbrazed or otherwise connected to an underlying metal component, such asa stainless steel component.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A hydraulic circuit component comprising: a flow passage; a firstseal element including a first sealing surface and a second seal elementincluding a second sealing surface, wherein the first and the secondseal elements are configured to enable at least one of the first andsecond sealing elements to make sliding contact with the other of thefirst seal element and the second seal element between a first relativeposition thereof and a second relative position thereof; wherein in afirst relative position of and the first sealing element and the seconda second sealing element the flow passage is blocked by one of the firstsealing element and the second sealing element, and in a second relativeposition of and the first sealing element and the second a secondsealing element the flow passage is not blocked by either one of thefirst sealing element and the second sealing element; and at least oneof the first sealing surfaces and the second sealing surfaces componentcomprise a non-metallic crystalline material, wherein the first surfaceand second surface are configured such that the force required to causeone of the first and second sealing surfaces to start sliding withrespect to the other of the first and second sealing surfaces is no morethan one-half the force required to initiate relative sliding motionbetween contacting metallic to metallic sealing surface.
 2. Thehydraulic circuit component of claim 1, wherein the crystalline materialis a single crystal.
 3. The hydraulic circuit component of claim 2,wherein both the first sealing surface and the second sealing surfacecomprise the crystalline material.
 4. The hydraulic circuit of claim 1,wherein at least one of the first sealing surface and the second sealingsurface is on an insert positioned in a respective one of the first sealelement and the second seal element.
 5. The hydraulic circuit of claim1, wherein at least one of the first sealing surface and the secondsealing surfaces comprises ruby.
 6. The hydraulic circuit of claim 1,wherein at least one of the first sealing surface and the second sealingsurface comprises sapphire.
 7. The hydraulic circuit of claim 1, whereinat least one of the first sealing surface and the second sealingsurfaces comprises a polycrystalline material.
 8. The hydraulic circuitof claim 7, wherein the polycrystalline material is zirconia.
 9. Thehydraulic circuit component of claim 1, wherein at least one of thefirst sealing surface on the first seal element and the second sealingsurface on the second seal element is a crystalline coating.
 10. Ahydraulic circuit component comprising: a flow passage; at least onecomponent having a crystalline first surface and a second componenthaving a second surface, at least one of the crystalline first surfaceand the second surface configured to move with respect to the other ofthe crystalline first surface and the second surface between a firstposition whereby the flow passage is blocked by one of the crystallinefirst surface and the second surface and a second position whereby theflow passage is not blocked by either of the crystalline first surfaceand the second surface, while maintaining contact between at leastportions thereof during the movement thereof between the first andsecond positions, the crystalline first surface and the second surfaceconfigured to provide, when in contact with each other and stationary,less resistance to initiating relative sliding motion therebetween thana carbide to carbine sliding interface of the same configuration. 11.The hydraulic circuit component of claim 10 wherein the crystallinefirst surface and the second surface are flat surfaces, and the flowpassage opens into one of the at least one crystalline first surface andthe second surface.
 12. The hydraulic circuit component of claim 10,wherein the at least one crystalline first surface is a single crystal.13. The hydraulic circuit component of claim 10, wherein second surfacecomprises the crystalline material.
 14. The hydraulic circuit componentof claim 10, wherein the first component includes an insert therein, andthe at least one crystalline surface is on the insert.
 15. The hydrauliccircuit component of claim 10, wherein the at least one crystallinesurface comprises ruby.
 16. The hydraulic circuit component of claim 10,wherein the at least one crystalline surface comprises sapphire.
 17. Thehydraulic circuit component of claim 10, wherein the at least onecrystalline surface comprises a single crystal.